Telephone-exchange system.



C. L. GOODRUM.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAR. 17. 1915.

1%]. 1,,34. Patented Jan. 9, 1917.

2 SHEETS-SHEET I.

W/fnesms: //1 van for:

@2 I C/mr/e: L. 5004mm QwW WWW the substation.

CHARLES L. GOODRUM, OF NEW YORK, N. Y.,

ASSIGNOR, BY MESNE ASSIGNMENTS, TO

WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification ofLetters Patent.

Patented Jan. 9, 191 '7.

Application filed March 17, 1915. Serial No. 14,971.

T 0 all "whom it may concern:

Be it known that 1, CHARLES L. GoonRUM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems employing machine switch- A feature of the invention is the provision of a stepping magnet circuit which will permit the rapid sending of impulses from To this end the stepping magnet circuit is arranged to be closed at the front contact instead of the back contact of the line relay. This arrangement insures a quicker and more reliable closure of the stepping magnet circuit, and avoids the chattering which ordinarily occurs when the circuit is closed at the back contact of the line relay.

Another feature is the elimination of sin gle step movements of the switches due to intermittent openings of the line should the subscribers carelessly remove and replace their receivers on the substation switchhooks. To this end there is provided a circuit arrangement which does not permit of switch movement until the ending of a short line interruption. Two slow-acting relays in,this circuit are arranged to fall back on a longer interruption, thus preventing the closing of the local circuit of the stepping magnet.

Still another feature is the shortening of the time which ordinarily elapses between the ending of the last interruption of a series, sent from the substation for selector control, and the commencement of the hunting movement of a trunk selector. To this end the stepping magnet is held energized, after the sending of the series of impulses from the substation, thereby keeping its pawl solidly. against the latch of the selector arm.

In the drawings:

Figure 1 shows a circuit embodying the invention; Fig. 2 is a side view of the upper portion of a finder switch and the vertical row of terminals in the panel it is adapted to serve, one section of the row being fully and another partly shown in section, with the cooperating sets of brushes; Fig. 3 is a A set of terminals 102, 103, 104, one belonging to each of three adjacent strips belonging to a given line, is adapted to be engaged by a set of brushes 1.05, 106, 107 of a selector switch, to connect with said line on one side of the panel as a calling line. The number of sets of ears or terminalson the three strips corresponds to the number of connector mechanisms, the number of which is determined by the traflic.

The panel or bank contains the line and test terminals of one hundred lines, divided horizontally by metal bars 108 into ten divisions or groups of ten each. Thus each vertical row containing the sets of terminals of one hundred lines is divided into ten sections. Each such section is served by a set of brushes 105, 106, 107 adapted to contact with the sets of terminals 102, 103, 104. These sets of brushes are mounted upon supports 109 which are in turn rigidly mounted upon a common carrier or rod 110. The sets of brushes are spirally arranged upon the brush rod 110, and the rod is first rotatedto position the proper set of terminals below the desired sectionof the vertical row served. by said rod, whereupon the rod is elevated, during which movement the selected set of brushes wipes over the sets of terminals of its section of the row. The bar 108 between the sections is made wide enough to permit the brushes to rotate without hindrance by the fixed terminals.

The brush rod 110 is provided near its lower end-with a gear wheel 111. The pawl 112 of the armature 113 of rotary magnet 114 does not act directly upon the gear wheel 111 of the rod, but steps around a member 115 by engaging a ratchet wheel 116 thereon, which member carries a second gear wheel 117 which meshes with the gear wheel 111 on the rod 110. After the brush rod 110 has been rotated by said magnet to the proper point, the rotary magnet ceases to operate. The rod is then elevated by the pawl 118 carried by armature 119 of vertical magnet 120 mounted upon the frame 121.

Upon the beginning of the upward movement of the brush rod 110, a spring 122, secured to the frame, moves upwardly, a pin 123 thereon entering a notch in the gear wheel 117 to prevent the member 115 from being restored by the spring 124 when the dog 125 is withdrawn later, this dog and the dog 126 of'the vertical ratchet being released by the attractive movement of the armature (not shown) of the release magnet 127.

\Vith the construction described, the brush rod 110 drops entirely free when re leased at the termination of the conversation by the actuation of release magnet 127 and consequent withdrawal of dog 126. \Vhen it reaches its lowermost position the shoulder on the gear wheel 111 presses the spring 122 against the mounting plate 128. The consequent withdrawal of the pin 123 from the gear wheel 117 permits the spring 124 to rotate the member 115, whereupon the gear wheel 117 restores the brush rod 110 to normal position. The side switch for the selector moves from position 1 to 2 upon the deenergization of the escapement magnet 129, and from 2 to 3 upon the energization of said magnet.

Referring now to Fig. 1 which shows the circuit arrangement of this invention using automatic switches of the type just described, we will assume that the subscriber at substation 130 has initiated a call and that the call has progressed as far as the first selector shown in Fig. 1. At this instant circuit is closed through line relay 131 as follows: battery, one winding of line relay 131, arm 133, line conductor 134, substation 130, line conductor 135, arm 133, other winding of line relay 131, back to battery. The line relay attracts its armature closing a circuit from battery through first slow-acting relay 136. This is the condition of the apparatus at the first selector until the subscriber manipulates hisimpulse sender to select an idle trunk leading to the desired line. The subscriber now manipulates his sender. At the first impulse the line relay dee-nergizes, and its armature striking the back contact closes an energizing circuit for the second slowacting relay 137 which, at the front contact of its armature 138, closes a circuit for the escape magnet 129, and at the front contact of its armature 139 closes a break point in the energizing circuit of the rotary magnet 114. As each impulse comes over the line the line relay is alternately energized and deenergized, the intervals of no current being too short to allow of the deenergization of the slow-acting relays 136 and 137, but causing the energization of the rotary magnet 114 over the following circuit: battery, rotary magnet 114, conductor 140, vertical off-normal switch 141, armature 139 and front contact of second slow relay 137, conductor 142, armature and front contact of line relay 131 to ground. The rod 110 is stepped round by the rotary magnet 114 until the proper set of brushes 105, 106, 107 is in position to pass over the Set of contacts containing the trunk leading to the desired line. At the termination of this series of impulses, the line relay 131 remains energized allowing the second slow-acting relay 137 to become deenergized. The deenergization of the second slow-acting relay causes the deenergization of the escape magnet 129 which moves the side switch from position 1 to position 2. The rotary magnet 114 remains locked up over circuit: battery, magnet 114, armature and front contact thereof, conductor 143, armature and front contact of line relay 131, to ground. This insures that the set of contact arms 105, 106, 107 is held positively in operative relation to the set of terminals containing the terminals of the trunk leading to the line wanted. Immediately the side switch comes into position 2 a circuit is closed for the vertical magnet 120 as follows: battery, vertical magnet 120, armature and back contact thereof, conductor 145, arm 146 of the side switch in the second position thereof, conductor 142, conductor 147, armature and front contact of line relay 131 to ground. The circuit just traced will be automatically made and broken at the armature and back contact of the vertical magnet 120, elevating the rod 110 and moving the set of contact arms 105, 106, 107 over the sets of contacts containing the terminals of an idle trunk, leading to the line wanted. The set of contact arms 105, 106, 107 will continue to move upwardly until an idle trunk represented by the set of terminals 148, 149, 150, is found. As soon as the rod 110 begins its upward movement, the circuit for the rotary magnet 114 is broken at the vertical 011- normal switch 141. The rotary magnet 114 is held energized, however, over the circuit, battery, rotary magnet 114, conductor 143, conductor 147, armature and front contact of .line relay 131, to ground, until the vertical magnet 120 takes its first step. A-n idle set of terminals (as 148, 149, 150) will have ground on its test terminal 150, and when the test brush 107 contacts therewith a circuit is completed for the escape magnet 129 as follows: battery, escape magnet 129, conductor 151, arm 152 of the side switch in position 2 thereof, conductor 153, conductor 154, brush 107, terminal 150 to ground. The escape magnet energizes, moving the side switch from position 2 to position 3, and breaking the operating circuit of the vertical magnet 120 at the arm 146. As the side switch moves into position 3, its arms 132, 133 extend the calling line circuit through to the connector (not shown), the terminals of which are represented at 148, 149, 150. Should a subscriber after initiating a call, hang up his receiver, before the stepping impulses have been sent causing the (leanergization of the line relay 131, it would cause a (leenergization of the second slow-acting relay 137, with a consequent deiinei'gization of the escape magnet 129, moving the side switch into second position. To prevent this occurring until after the stepping magnet 114 has taken its first step, the off-normal contact 153 is provided in the circuit of escape magnet 129, which off-normal contact is open until the stepping magnet 114 takes its first step.

What is claimed is:

1. In atelephone exchange system, a line circuit, a stepping relay connected thereto, a switch including a stepping magnet, an operating circuit for said magnet controlled at the front contact of said stepping relay, and a locking circuit for said stepping magnet.

2. In a telephone exchange system, a line circuit, a stepping relay connected thereto, a switch including a stepping magnet, an opcrating circuit for saidmagnet controlled at the front contact of said stepping relay and at an olf-normal switch, and a slow-acting relay operated by said stepping relay and controlling a break point in said operating circuit.

3. In a telephone exchange system, a line circuit, a stepping relay connectedthereto, a slow-acting relay operated by said stepping relay at the first energization thereof,

a second. slow-acting relay, an energizing circuit therefor having-a break point therein closed at the armature and front contact of said first named slow-acting relay, a

switch including a stepping magnet, an opcrating circuit for said magnet controlled by said stepping relay and having a break point therein closed at an armature and front contact of said second slow-acting relay, and a circuit for locking the stepping magnet at the end of the last directive impulse.

4. In an automatic telephone exchange system, a line circuit, a switch adapted to extend said line circuit, a stepping relay connected to said line circuit, a stepping magnet for controlling the operation of said switch, an energizing circuit for said stepping magnet controlled at the armature and front contact of said stepping relay, and a movable contact engages with the terminal of an idle line, whereby the operating magnet energizes to move the side switch to break the circuit of said first named magnet.

' 6. In a telephone exchange system, a line circuit, a selector switch operated through long and short movements to extend said line circuit, primary means for controlling the long movements of said switch, secondary means for controllingv the short movements of said switch, and means for maintaining said primary means actuated during the short movements.

7 In a telephone exchange system, a line circuit, a selector switch operated through long and short movements to extend said line circuit, a primary magnet for controlling the long movements of said switch, a secondary magnet for controlling the short movements of said switch, energizing circuits for said magnets, and a locking circuit for said primary magnet closed during the short movements of said switch.

8. In a telephone exchange system, a line circuit, a stepping relay connected thereto, a selector switch including a stepping magnet, an operating circuit for said magnet controlled at the front contact of said stepping relay, and a locking circuit for said stepping magnet in parallel with said operating circuit.

9. In a telephone exchange system, a line circuit, a selector switch including a stepping magnet provided with an armature, an operating circuit for said magnet, and a locking circuit for said magnet controlled at one point by said armature.

In witness whereof, I hereunto subscribe my name this 16th day of March, A. D. 1915.

CHARLES L. GOODRUM.

Witnesses:

E. EDLER, H. L. STAHL. 

